This is an artist's conception of Tiktaalik, the species that may bridge the evolutionary gap between animals of land and sea.

Credit: Zina Deretsky, National Science Foundation

NSF supported more than 100 research projects in response to the destruction caused by Hurricanes Katrina and Rita in 2005. One of the research teams studied the New Orleans levee system. This is a segment from an animation showing how the researchers suggest the city's 17th Street levee failed.

Credit: Trent Schindler, National Science Foundation

Astronomers observing a rare collision of galaxies made the first direct detection of "dark matter." In this image, the luminous gas from the collision (red) lags behind the two clusters of dark matter (blue).